One case study on this very topic was published in the recent Code4Lib Journal, it may be of use:

http://journal.code4lib.org/articles/3072
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From: Code for Libraries [[log in to unmask]] On Behalf Of Tom Vanmechelen [[log in to unmask]]
Sent: Wednesday, June 30, 2010 8:24 AM
To: [log in to unmask]
Subject: [CODE4LIB] locator

We're considering  to expand our service with a item locator. "Mapping the library" (http://mashedlibrary.com/wiki/index.php?title=Mapping_the_library) describes how to build this with Google maps. But is this really the way to go?  Does anyone has any experience with this? Does anyone have some best practices for this kind of project knowing that we have about 20 buildings spread all over the town?

Tom

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Tom Vanmechelen

K.U.Leuven / LIBIS
W. De Croylaan 54 bus 5592
BE-3001 Heverlee
Tel  +32 16 32 27 93